1. Field of the Invention
The present invention relates generally to corrosion inhibition of metal alloys and, more particularly, to corrosion inhibition of a Co-Cr-Mo alloy (ASTM F-75) and the process of effecting the same.
2. The Prior Art
In the specialized field of orthopaedic prostheses used for human joint replacement and fixation devices, cobalt-based alloys have become widely used. The specific cobalt-based alloy designated for this purpose by the American Society for Testing and Materials (ASTM) is known as the F-75 Co-Cr-Mo alloy, also called "Vitallium" or "HS-21" alloy. There is presently considerable concern that metallic ions, principally chromium, cobalt and nickel, released by corrosion of the cobalt-based metal alloy after implantation of the prosthesis, can cause adverse long term local and systemic effects in the recipients of the implanted orthopaedic devices. Patients receiving such Co-Cr-Mo alloy joint replacements have been observed with elevated levels of cobalt in their blood, urine, hair, muscle and bone adjacent the implant as well as in remote internal organs.